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virtio-devices: pmem: Port to EpollHelper

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Migrate to EpollHelper so as to remove code that is duplicated between
multiple virtio devices.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>
This commit is contained in:
Rob Bradford 2020-08-04 12:16:44 +01:00 committed by Sebastien Boeuf
parent e093f0e83e
commit ce65093f8d
1 changed files with 29 additions and 103 deletions
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132
virtio-devices/src/pmem.rs
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@ -8,8 +8,9 @@
use super::Error as DeviceError;
use super::{
ActivateError, ActivateResult, DescriptorChain, DeviceEventT, Queue, UserspaceMapping,
VirtioDevice, VirtioDeviceType, VIRTIO_F_IOMMU_PLATFORM, VIRTIO_F_VERSION_1,
ActivateError, ActivateResult, DescriptorChain, EpollHelper, EpollHelperError,
EpollHelperHandler, Queue, UserspaceMapping, VirtioDevice, VirtioDeviceType,
EPOLL_HELPER_EVENT_LAST, VIRTIO_F_IOMMU_PLATFORM, VIRTIO_F_VERSION_1,
};
use crate::{VirtioInterrupt, VirtioInterruptType};
use anyhow::anyhow;
@ -19,7 +20,7 @@ use std::fmt::{self, Display};
use std::fs::File;
use std::io;
use std::mem::size_of;
use std::os::unix::io::{AsRawFd, FromRawFd};
use std::os::unix::io::AsRawFd;
use std::result;
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Arc;
@ -43,11 +44,7 @@ const VIRTIO_PMEM_RESP_TYPE_OK: u32 = 0;
const VIRTIO_PMEM_RESP_TYPE_EIO: u32 = 1;
// New descriptors are pending on the virtio queue.
const QUEUE_AVAIL_EVENT: DeviceEventT = 0;
// The device has been dropped.
const KILL_EVENT: DeviceEventT = 1;
// The device should be paused.
const PAUSE_EVENT: DeviceEventT = 2;
const QUEUE_AVAIL_EVENT: u16 = EPOLL_HELPER_EVENT_LAST + 1;
#[derive(Copy, Clone, Debug, Default, Deserialize)]
#[repr(C, packed)]
@ -244,106 +241,35 @@ impl PmemEpollHandler {
})
}
fn run(&mut self, paused: Arc<AtomicBool>) -> result::Result<(), DeviceError> {
// Create the epoll file descriptor
let epoll_fd = epoll::create(true).map_err(DeviceError::EpollCreateFd)?;
// Use 'File' to enforce closing on 'epoll_fd'
let epoll_file = unsafe { File::from_raw_fd(epoll_fd) };
fn run(&mut self, paused: Arc<AtomicBool>) -> result::Result<(), EpollHelperError> {
let mut helper = EpollHelper::new(&self.kill_evt, &self.pause_evt)?;
helper.add_event(self.queue_evt.as_raw_fd(), QUEUE_AVAIL_EVENT)?;
helper.run(paused, self)?;
// Add events
epoll::ctl(
epoll_file.as_raw_fd(),
epoll::ControlOptions::EPOLL_CTL_ADD,
self.queue_evt.as_raw_fd(),
epoll::Event::new(epoll::Events::EPOLLIN, u64::from(QUEUE_AVAIL_EVENT)),
)
.map_err(DeviceError::EpollCtl)?;
epoll::ctl(
epoll_file.as_raw_fd(),
epoll::ControlOptions::EPOLL_CTL_ADD,
self.kill_evt.as_raw_fd(),
epoll::Event::new(epoll::Events::EPOLLIN, u64::from(KILL_EVENT)),
)
.map_err(DeviceError::EpollCtl)?;
Ok(())
}
}
epoll::ctl(
epoll_file.as_raw_fd(),
epoll::ControlOptions::EPOLL_CTL_ADD,
self.pause_evt.as_raw_fd(),
epoll::Event::new(epoll::Events::EPOLLIN, u64::from(PAUSE_EVENT)),
)
.map_err(DeviceError::EpollCtl)?;
const EPOLL_EVENTS_LEN: usize = 100;
let mut events = vec![epoll::Event::new(epoll::Events::empty(), 0); EPOLL_EVENTS_LEN];
// Before jumping into the epoll loop, check if the device is expected
// to be in a paused state. This is helpful for the restore code path
// as the device thread should not start processing anything before the
// device has been resumed.
while paused.load(Ordering::SeqCst) {
thread::park();
}
'epoll: loop {
let num_events = match epoll::wait(epoll_file.as_raw_fd(), -1, &mut events[..]) {
Ok(res) => res,
Err(e) => {
if e.kind() == io::ErrorKind::Interrupted {
// It's well defined from the epoll_wait() syscall
// documentation that the epoll loop can be interrupted
// before any of the requested events occurred or the
// timeout expired. In both those cases, epoll_wait()
// returns an error of type EINTR, but this should not
// be considered as a regular error. Instead it is more
// appropriate to retry, by calling into epoll_wait().
continue;
}
return Err(DeviceError::EpollWait(e));
}
};
for event in events.iter().take(num_events) {
let ev_type = event.data as u16;
match ev_type {
QUEUE_AVAIL_EVENT => {
if let Err(e) = self.queue_evt.read() {
error!("Failed to get queue event: {:?}", e);
break 'epoll;
} else if self.process_queue() {
if let Err(e) = self.signal_used_queue() {
error!("Failed to signal used queue: {:?}", e);
break 'epoll;
}
}
}
KILL_EVENT => {
debug!("kill_evt received, stopping epoll loop");
break 'epoll;
}
PAUSE_EVENT => {
debug!("PAUSE_EVENT received, pausing virtio-pmem epoll loop");
// We loop here to handle spurious park() returns.
// Until we have not resumed, the paused boolean will
// be true.
while paused.load(Ordering::SeqCst) {
thread::park();
}
// Drain pause event after the device has been resumed.
// This ensures the pause event has been seen by each
// and every thread related to this virtio device.
let _ = self.pause_evt.read();
}
_ => {
error!("Unknown event for virtio-block");
impl EpollHelperHandler for PmemEpollHandler {
fn handle_event(&mut self, _helper: &mut EpollHelper, event: u16) -> bool {
match event {
QUEUE_AVAIL_EVENT => {
if let Err(e) = self.queue_evt.read() {
error!("Failed to get queue event: {:?}", e);
return true;
} else if self.process_queue() {
if let Err(e) = self.signal_used_queue() {
error!("Failed to signal used queue: {:?}", e);
return true;
}
}
}
_ => {
error!("Unexpected event: {}", event);
return true;
}
}
Ok(())
false
}
}
@ -357,7 +283,7 @@ pub struct Pmem {
config: VirtioPmemConfig,
queue_evts: Option<Vec<EventFd>>,
interrupt_cb: Option<Arc<dyn VirtioInterrupt>>,
epoll_threads: Option<Vec<thread::JoinHandle<result::Result<(), DeviceError>>>>,
epoll_threads: Option<Vec<thread::JoinHandle<result::Result<(), EpollHelperError>>>>,
paused: Arc<AtomicBool>,
mapping: UserspaceMapping,